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Federal AviationAdministrationAirport Pavement
Design & Evaluation
Draft AC 150/5320-6F
FAARFIELD Software
ACC Summer Workshop
August 10, 2016
Washington, DC
Presented by: Doug Johnson, P.E.
FAA, Airports, AAS-100
Sr. Civil Engineer - Pavement
Federal AviationAdministration
Overview
• Current Status AC 150/5320-6F
– Internal and Industry Comments
Incorporated
– Currently at Technical Editor
– Next step Legal Review
– Anticipate Issuing
Late September / Early Oct
Federal AviationAdministration
Principal Changes
• FAARFIELD v 1.41 (ver 1.41.0010 latest)• Revised failure curves + added compaction computation
• Pavement Design Report saved as pdf
• Reformatted to comply with Order 1320.46
• Text & Examples updated
• Define Regular Use
• Added discussion on Structural Life &
Functional Life
• Tables for Minimum Layer Thickness as
opposed to light & other
Federal AviationAdministration
Selection of Pavement Type(Draft AC 5320-6F)
It is your job as Engineer to document the rationale for the
selection of pavement type, section and service life.
Federal AviationAdministration
• Alternative Pavement Sections
– Assumed all will achieve desired result
• Cost Effectiveness Analysis
– Lowest total cost over life of project
– Challenge User Cost Impacts
– Routine maintenance – marginal impact
– Focus on Initial Construction, preventative
maintenance and rehabilitation costs
Selection of Pavement Type
It is your job as Engineer to document the rationale for the
selection of pavement type, section and service life.
Federal AviationAdministration
• Reality –
Funds Available is always a factor
• Just because LCCA supports section
does not assure that funds available to
support initial construction
Selection of Pavement Type
Federal AviationAdministration
• Compaction Recommendations calculated
by FAARFIELD (draft AC 5320-6F)
– Based upon Compaction Index (CI) concept
– Minimum rework / re-compact top 12” in cuts plus
any additional depth as calculated by FAARFIELD
– Maximum depth of compaction 72” below finished
subgrade
• Aircraft < 60,000 lbs ASTM D 698
• Aircraft > 60,000 lbs ASTM D 1557
Subgrade Support
Federal AviationAdministration
Stabilized Base
• Stabilized Base Required
– Aircraft > 100,000 lbs
– Full Scale tests have proven superior performance with stabilized base
– If less than 5% of traffic > 100K but less than 110k, may consider not using (still a good idea to use)
– Crushed aggregate with CBR > 100 may be substituted…stabilized still better long term performance.
– Subbase under Stabilized base CBR > 35
Federal AviationAdministration
Pavement Life (6F)
• Design Life in FAARFIELD = Structural Life
• Functional Life = Period of time pavement able to provide acceptable service as measured by performance indicators such as foreign object debris (FOD), skid resistance or roughness.
• Typically design for 20 year structural life
• To achieve intended service life requires quality materials and construction combined with routine and preventative maintenance
Federal AviationAdministration
Aircraft Traffic Considerations
• Load– Maximum anticipated Departure (Takeoff) Weights
– If arrival and departure at same weight or if no parallel taxiway may need to adjust number of departures to match number of times pavement is loaded with each operation
• Volume– Annual Departures of Fleet
– New in 6F ‘regular use = 250 departures)
– New in 6F ‘occasional use and seasonal’ need to be documented
Federal AviationAdministration
FAARFIELD 1.4 – What’s New?
FAARFIELD 1.4 has:
• Completely revised flexible and rigid failure models
based on newest full-scale test data.
• Improved, more accurate 3D finite element model.
• Completely rewritten concrete overlay design procedure.
• Support for user-defined gear configurations.
• Updated aircraft library aligned with COMFAA 3.0.
• Automated, software-based compaction criteria.
• All data files now stored in document directories.
• Automatically generates PDF design report.
Federal AviationAdministration
Improved Rigid Failure Model
Effect of Concrete Flex Strength Effect of Traffic
• Sensitivity to factors such as concrete strength, traffic level and
subgrade support is similar to current version.
0
2
4
6
8
10
12
14
16
18
20
0.01 0.1 1 10 100C
on
cret
e T
hic
kne
ss, i
n.
Traffic Factor
FAARFIELD 1.305 FAARFIELD 1.41
Federal AviationAdministration
New Aggregate Modulus Model
• FAARFIELD 1.4 implements
a new sublayering and
modulus computation
procedure for aggregate
subbase (P-154 & P-209).
• Why?
– Previous procedure (WES
Modulus subroutine) has gaps
that can cause illogical results
under some circumstances.
– New model provides a continuous
function of modulus with changes
in P-154 thickness.
– Better overall agreement with the
P-209/P-154 equivalency factor
used in PCN computations.
Federal AviationAdministration
Automated Compaction Criteria
Computes compaction control points for rigid & flexible pavements.
Federal AviationAdministration
Aircraft Libraries
• Aligned the aircraft
libraries in COMFAA and
FAARFIELD to the extent
possible.
• Used the most current
data from manufacturers.
• Multigear AC split into
main & belly, but link AC
• Included new aircraft:– A350-900 (Preliminary)
– B747-8
– B787-9
– Embraer Fleet
Federal AviationAdministration
Airport Pavement Design
Federal AviationAdministration
Airport Pavement Design
Airport Pavement Thickness Design -
FAARFIELD
Federal AviationAdministration
Allowable Modulus and Poisson Ratios
Airport Pavement Thickness Design -
FAARFIELD
Federal AviationAdministration
• Include copy of FAARFIELD Design Report
in Engineers Report
• Pavement Design Form no longer needed
• Still need to run COMFAA to determine PCN
and use COMFAA support spreadsheet to
get weight information for 5010
(Future plans include FAARFIELD computing PCN, but this f(ICAO) adopting changes to
ACN/PCN process. FAA is currently working with ICAO on these changes)
FAARFIELD Design Report
Federal AviationAdministration
Airport Pavement Thickness Design -
FAARFIELD
Note 3: Base and
subbase minimum 12”
up to 36” beyond full
strength
Typical Section
Note Variable
thickness surface still
an option, i.e exit TW
just arrival weight,
keel full strength
transitioning to 1%
traffic on outer for
middle of RW
Federal AviationAdministration
Joints
21
Saw cut depth
recommendations
added on joint detail:
-T/4 on aggregate
-T/3 on stabilized
-T/5 or T/6 early entry
-Preformed Detail
Federal AviationAdministration
• Sample PCC Joint Plans pdf or dxf
@https://www.faa.gov/airports/engineering/
pavement_design/
Joints
Federal AviationAdministration
Joints
Airport Pavement Thickness Design -
FAARFIELD
23
Federal AviationAdministration
Questions?
Doug Johnson, P.E.
(202) 267-4689
Greg Cline, P.E.
(202) 267-8814